It's called “blurbing” but if you study the history of the book, the blurb is the description on the jacket, whereas a puff is an endorsement. I'm happy with the ones I've done this year so far:
Graham Harman, Bells and Whistles.
Daniel Tiffany, My Silver Planet (on kitsch).
Anat Pick and Guinevere Narraway, eds., Screening Nature.